Installation, Commissioning and Maintenance
Manual
12
12.0 Operation
The following instructions must be followed and integrated
into End User safety program when installing and using
Rotork products. Read and save all instructions prior to
installing, operating and servicing this product.
Follow all warnings, cautions and instructions marked on and
supplied with the product.
Install equipment as specified in Rotork installation
instructions and as per applicable local and national
codes of practice. Connect all products to the proper
pipeline gas sources.
When replacement parts are required, ensure that the
qualified service technician uses only replacement parts
specified by Rotork.
Substitutions will invalidate any hazardous area certification
and may result in fire, electrical shock, other hazards or
improper operation.
12.1 Description
The GP/S series actuators are pneumatic single-acting –
spring return actuators specifically designed to provide
efficiency and reliability in heavy duty services.
GP/S actuators can be assembled in a ‘spring to open’ or in a
‘spring to close’ version and can be fitted with an emergency
manual override suitable to operate the actuator in the event
of fluid supply failure.
Main components of a GP/S actuator are:
• A
scotch-yoke mechanism
, which transforms the
linear movement of the pneumatic cylinder into a rotary
movement suitable for operating quarter-turn valves, such
as ball valves, butterfly valves or plug valves. It is available
in both “symmetric” and “canted” execution to meet
application specific valve torque demand requirements.
The scotch-yoke mechanism is situated in a perfectly
sealed housing, made of welded carbon steel or in cast
iron, acting as a protection against corrosion and that
guarantees safety of personnel during the operations.
Chromium plated guide bar suitable for supporting the
transverse forces and ensure the proper alignment of the
piston rod. The Chromium plating prevents corrosion and
minimizes sliding friction.
Sliding blocks and yoke bushings are made of bronze to
reduce friction and to guarantee a long working life.
• A
pneumatic cylinder
, made of carbon steel.
The cylinder tube is nickel plated internally by electrolysis,
to assure perfect dynamic seal, corrosion resistance and
low friction.
The piston is made of carbon steel. The dynamic floating
piston seal further reduces friction and avoids stick-slip
effect even after prolonged periods without operation.
The sliding ring made of Teflon guides the piston in the
cylinder and ensure a good radial loading capacity.
A chromium plated piston rod ensures a perfectly
dynamic seal, corrosion resistance and low friction.
The dynamic cylinder seals are specifically designed to
enable the use without lubrication.
• The
spring cartridge
(only for single-acting actuator),
consisting of a welded container containing a frame
assembled spring package that prohibits the spring from
extending beyond a pre-set length.
• Two mechanical
stop bolts
to enable the adjustment of
valve angular stroke.
• A
mechanical visual position indicator
directly
connected to the valve stem that shows the position of
the valve all along the actuator stroke.
Upon request, GP series actuators can be equipped with
additional accessories (limit switches box, positioner, position
transmitter, control panel, etc.)
Use only control devices supplied by Rotork Fluid Systems.
Installation of any accessory on the bare actuator
must preserve the actuator Ingress Protection level.
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